The term “antigen” is defined as anything that can serve as a target for an immune response. The immune response can be either cellular or humoral. The term “vaccine” is defined herein as a suspension or solution of antigenic moieties, usually consisting of infectious agents, or some part of the infectious agents, that is injected into the body to produce active immunity. The antigenic moiety making up the vaccine can be either a microorganism or a natural product purified from a microorganism, a synthetic product or a genetically engineered protein, peptide, polysaccharide or similar product. The term “cell mediated immunity” is defined as an immune response mediated by cells rather than by antibody. It includes, but is not limited to, delayed type hypersensitivity and cytotoxic T cells. The term “adjuvant” as used herein is any substance whose admixture with an injected immunogen increases or otherwise modifies the immune response. A “hapten” is defined herein as a substance that reacts selectively with appropriate antibodies or T cells, but the hapten itself is usually not immunogenic. Most haptens are small molecules or small parts of large molecules, but some macromolecules can also function as haptens. The term “conjugation” is defined herein as the covalent or other form of linking two or more molecules. It can be accomplished either by chemical means or in vivo by biologic means such as genetic engineering.
The process of immunization has been used for over a hundred years to protect humans and animals against disease. The process generally comprises injecting an antigen that is related to the pathogen in the human or animal and waiting an appropriate amount of time, allowing the human or animal in which the pathogen was injected to mount an immune response. The time required for mounting an immune response normally is between approximately two weeks and several months for most antigens. In most cases, a booster administration of the antigen is required to maintain the immune response. This booster is normally given weeks or months after the initial administration of the antigen. Thus, immunization is of little use for immediate treatment of a disease.
A separate immunization procedure must be made for each pathogen, although in some cases several antigens are included in a single vaccine. Every immunization carries with it a certain amount of risk that must be considered before any immunization is recommended on a wide-scale basis.
What is needed is a method of immunizing a human or animal that can result in an immediate immune response. In addition, a method of immunizing a human or animal by a single immunization would greatly reduce the inherent risks in the vaccination procedure.